


When Life Gives You Nitric Acid...

by AmmoniteInk



Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Alpha/Beta/Omega Dynamics, Angst with a Happy Ending, Dirty Talk, Finger Fucking, Fluff, Fluff and Smut, Frottage, Grinding, I promise it’s not all porn, Intersex Omegas, Kissing, Mating Cycles/In Heat, Multi, Mutual Masturbation, Other Additional Tags to Be Added, Other Ships To Be Added, Polyamory, Senku isn't very good at feelings, So don’t be upset if it’s not all your otp, Vaginal Fingering, mentions of mpreg, non-traditional ABO dynamics
Language: English
Status: In-Progress
Published: 2019-10-10
Updated: 2020-04-07
Packaged: 2020-12-07 10:09:54
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 6
Words: 13,139
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20974160
Author URL: https://archiveofourown.org/users/AmmoniteInk/pseuds/AmmoniteInk
Summary: When spring comes back around, Senku finds himself in heat with no Taiju and Yuzuriha to help. Time for plan B.





	1. Plan B

Not having your pack around sucked, Senku decided. It was spring again, two years since he had emerged, and his body decided now was the time to throw him into heat. Senku had been lucky that the previous springs hadn’t brought forth a heat. But now his body was acclimated and his internal clock had readjusted. At least, that seemed like the most plausible answer. He’d been busy with science and had been taking heat inhibitors all his life, his dynamic had kind of fallen by the wayside. He didn't have time for it, especially not now!

Running around the stone world and there being a drastic decrease in the human population (unpetrified at least), his omega status had never been more apparent. Omegas aren't discriminated against or seen as lesser in Ishigami Village, they're instead treasured. It's very unlike the time period before the modern world invented drugs to block scents and inhibit heats. And even then, there had been people who clung to archaic mindsets. It was rather fascinating, actually. It was one thing Senku didn't miss about the modern world. 

Having your dynamic out in the open for all to scent took some getting used to. He’d noticed that Chrome, Kohaku, and Gen (members of his sort of pseudo-pack while Taiju and Yuzuriha were away) had become increasingly more touchy-feely the past few days.

Gen kept gently touching him in ways unnoticeable by anyone besides Senku. He managed to sneak in brushes of his hands over Senku’s shoulders and arms, even successfully capturing him in a hug yesterday before the scientist wiggled out of the hold. Senku usually wasn't a fan of being touched, but he never told Gen to stop and reluctantly admitted to himself that it wasn't unpleasant. In retrospect, he realized it was the heat talking.

Kohaku kept bringing him breakfast in the morning before he woke up. She would also pull him away by the collar from slightly dangerous things like potholes in the ground or stray shards of glass near where Kaseki was working. It got rather annoying.

When Chrome started taking over many of Senku’s tasks and collecting way more materials than strictly necessary, Senku got fed up. He growled at Chrome, which came as quite a shock to everyone. Out of all of them, Senku was the least likely to express himself that way. People tended to forget that he, too, had animalistic qualities.

Senku was relieved when everyone left him alone for the rest of that day. He should have known he wouldn’t catch a break for long because here he was, the next day, in the midst of his heat. The others must have been affected by the growing prominence of his scent in preparation for estrus. It should have been ten billion percent obvious, but again, he’d been a bit busy saving all of humanity to be concerned about his next reproductive cycle.

Lying in his bed in the observatory, squirming with uncomfortable warmth and arousal was not what Senku expected to be doing today. His body longed for Yuzuriha or Taiju to come wrap him up in their arms and take care of him and sate him until he fell asleep. They’d been a pack for a few years before everyone was turned to stone, slowly inching into romantic territory as they grew up (at least Yuzuriha and Taiju were, the jury was still out on Senku's romantic inclinations at the time). The availability of inhibitors allowed them to go as slow as they pleased back then. Now, Senku just wanted to skip through all of that messy "figuring out your feelings" stuff and kiss them, touch them, let them touch him…

_Stop it! Thinking about them won’t help. What are your options right now?_

Senku couldn’t stay here. Well, he could, but it would lead to dehydration, discovery by an unwanted party, or both. As much as he hated to admit it, he needed someone to look after him until this was over. So who in his pseudo-pack would work?

It can’t be the gorilla, not in 3,700 years. No way.

Chrome? It didn’t feel right having his first heat around an alpha who Taiju hadn’t approved and wasn’t officially part of Senku’s pack. Plus, there was the chance of pregnancy if anything explicit happened (even though that in itself was unlikely) which opened a whole can of worms Senku didn’t want to open.

That left Gen, the scheming, sensual, pretty mentalist. It wouldn’t trigger Taiju’s protectiveness since Gen’s also an omega, and there’s a much lower chance of pregnancy.

_ Hmm, although, I wouldn’t mind carrying his pups. They’d be gorgeous and intelligent and…_ Whoa whoa whoa, _just because you’re horny doesn’t mean you get to fantasize about pups, brain. We’re going to find Gen and he’s gonna make sure we don’t die, that’s it. And maybe he’ll kiss you, too, it can’t hurt…_

Senku shook his head defiantly against the intrusive thoughts. Time to get moving.

He snuck his way out of the observatory and made his way towards Chrome’s hut. His apprentice was likely out gathering materials at this hour, so Gen would be the only one in the hut.

When Senku opened the door to the hut, he was hit with the lingering scents of Chrome and of Gen.

Senku nearly melted right there, the comforting smells of his friends enough to provide relief.

With no time to lose, Senku forced himself to move, closing the door and locking it. Gen, still asleep, shifted under his blankets. No doubt the scent of Senku’s heat and the noise was beginning to wake him.

Senku was practically suffocating on the smells now that there was so little airflow.

Chrome smelled like metal and tree bark, reminding him of their lab adventures and spelunking. It was refreshing and happy, making Senku feel content.

Gen smelled like lavender and freshly made herb butter. Enticing and soothing, fitting for a mentalist.

Senku felt himself start to slick. 

_Shit, stay focused, just wake him up. One step at a time, you can do this. Don't let it take over._

As if in direct protest to his thoughts, Senku's body sent a delicious shiver through him, prompting insistent throbbing between his legs. Taken by surprise, Senku's control slipped.

He crawled on top of Gen on his hands and knees and nuzzled Gen’s soft hair, pawing at the blanket.

“Mmm, Gen…” Senku moved to the mentalist’s neck, where his scent glands were, and began to lick and nip there.

Gen groaned in sleepy confusion when he felt a mouth on his neck. After a few moments, his eyes snapped open and he almost couldn’t comprehend what he was seeing.

Senku was on top of him, flushed and panting, pupils dilated and eyes lidded. _Oh my god oh my god, he’s in heat! And is he...slicking? Holy fuck!_

Gen glanced around for Chrome, who was nowhere to be found.

“Senku! What—?”

“Good morning, Gen, you seemed to be enjoying my pheromones oh so much lately. Would you like to give me a different kind of help today?”

Senku smiled his smug smile.

“Umm…”

The door and windows were closed...Senku’s nose must be overwhelmed.

Gen needed to be delicate here, he couldn’t outright reject his friend, he didn’t know how he would react while he was in his omega headspace.

Regaining composure, Gen flipped Senku over onto his back, close to the bucket of drinking water.

“That sounds lovely, Senku-chan, but first you really must have something to drink. You won’t have much stamina if you’re dehydrated.”

With a few more sweet words he got Senku to fill a cup and start drinking.

Gen hurried to open the windows while the addled omega was occupied. When he sat back down next to Senku, he seemed more self-aware.

“Feeling better?”

“Yes, thank you.”

There was an awkward silence.

Gen had been in many difficult situations before, but he had never anticipated this. Yes, he had a soft spot for Senku and decided to tease him with fleeting touches to see if he could get the message across. He didn’t think Senku would actually come to him when he was in full-blown heat. The man was usually so level-headed and uninterested in anything that wasn’t scientific. 

Senku broke the silence with a sigh, “My apologies Gen, it seems I underestimated my body’s...effect on my mind. I came here to ask if you would—“

“Make sure you don’t fuck someone or kick the bucket?”

“That’s one way to put it,” Senku chuckled.

Shortly after, Senku squirmed in place, another shot of warmth going down his spine. He grunted and squeezed his eyes shut. He was still leaking slick and had started producing precum, the waves of arousal washing unbidden over him. What he wouldn’t give for some heat inhibitors right now. He really should add those to his list of things to make. 

Gen took a sharp inhale next to him. Being around another omega in heat, especially seeing Senku in his headspace, had riled him up. He pressed his thighs together to provide subtle relief.

“Senku-chan, I’m going to get you breakfast. Try not to trigger your bad luck tendencies while I’m gone.”

“Wouldn’t dream of it,” Senku mumbled.

When Gen left the hut he let out a huge breath. _Wow, that was, wow. He smells so fucking good, how am I gonna do this?_

Senku usually smelled like crisp air and flame. Like a bonfire on an autumn night. Now the scent had a sultry, heavy undertone that intensified the other smells. God how he’d like to lick up that deliciousness at its source. He’d play with Senku’s scent gland and persuade the stoic scientist to open his legs. He’d make Senku purr as he stroked his…

Kohaku’s fingers snapping in front of his face shook Gen from his fantasy. Right, Senku already had a pack and he needed food right now, not sex.

He quickly informed Kohaku what was happening and they agreed to keep it on the down-low. Chrome would be sleeping in the observatory tonight.

~

Back in the hut, Senku was having a hard time already. Now, his body was upset that a potential partner had left the nest.

_Wait, nest? I've never built one in my life! Why would I need a..._

_We need one, we can't mate on the cold, hard floor. Gen will come back if we make a comfy bed. _Senku's brain provided.

_Oh...yes of course. That makes sense._

Senku shuffled around the hut for blankets and clothing, collecting them all into a rather haphazard nest in the center of the floor. He made sure to include the bedding that Gen and Chrome had been using the previous night. Once finished, he practically dove in, snuggling amongst the cloth scented with his pseudo-packs' essence. 

_Yes..._

This is what he'd been waiting for, a warm, safe nest scented by his pack. Now, he could mate, he just needed to wait for Gen to come back.

When Senku remembered Gen, his body became hot almost instantly. The heat was really digging its claws in, turning up the temperature and pumping molten excitement through his veins. 

He found Gen's pillow in the depths of his nest and brought it to his face to inhale the calming scent of his packmate. He rolled over and squirmed in both happiness and dissatisfaction. He needed something, something to stave off this unbearable heat, this torturous feeling.

~

When Gen came back, all rational thought flew out the open windows.

Senku was in the middle of a nest made of Chrome’s and Gen’s bedding. He had taken Gen's pillow specifically, hiked up his tunic, and mounted it.

_How did this happen so fast!? _

“Ah! Haah—I couldn’t wait, I need to...Nngh!”

Senku's hands were planted in front of him, fingers digging into the bedding as he rutted against the pillow, trying to get the friction he so desperately needed.

Gen felt like he got punched in the gut and just managed to set the food down safely. Okay, maybe Senku did need sex, but he couldn’t…

An idea suddenly struck him.

“Senku-chan, may I enter your nest?”

Senku stopped moving, Gen’s voice sobering him a little. _What’s he thinking? _

Too thrilled by Gen’s “I have a plan” face and too horny to think about it too hard, Senku nodded and shifted to make room. He discarded the pillow now that he had the real thing in his nest.

_I trust him._

Gen laid down on his side to face Senku and bumped noses with him, initiating some nuzzling on both their parts. Gen skated his hand down to one of Senku's, guiding it to the swollen cock underneath his tunic.

Gently holding his wrist, Gen started moving Senku’s hand around his cock.

“Please continue, you need it.”

When Senku resumed his fondling, Gen began removing his clothes.

“Gen, what are you—?”

“Shhh, don’t worry…” Gen cocked one of his legs and started teasing his pussy, which was beginning to wet itself.

Senku’s mouth snapped shut at the display.

“We’re gonna get there together,” Gen said.

Senku smiled.


	2. Chief's Orders

“Gen, this is gross.” 

Gen laughed, and it turned into a moan. He had slipped his fingers into his pussy and was pumping them in and out in earnest. 

“Ahh~feels good to be gross, though.”

Senku turned his face and laughed into the blankets. He was hesitantly fingering his pussy with one hand while stroking his cock with the other. The obscene sounds of squelching filled the air. 

Gen leaned over and spoke into Senku’s ear, “Just imagine it Senku-chan, Taiju and Yuzuriha returning to you when the battle’s all said and done. They’d bring you into their hut and reward you for how good you did. You work so hard, you need them to wring all that tension out of you.” 

Senku moaned, eyes closing as the image of his pack filled his mind. He increased his stroking and slowed his fingering, unable to coordinate both through the haze of heat. 

“Oh come now Senku-chan, you know that’s not where you need it.”

Gen wrapped his unoccupied hand around Senku’s wrist and helped him pump his fingers into himself faster. Senku cried out at the assault on his insides. He felt his hot, wet passage fluttering around his fingers, trying to milk a cock that wasn’t there. 

As if reading his mind, Gen said, “Taiju would have you just like this, all desperate and flushed. You would be so good for him, milking his cock for all it’s worth.”

Senku was getting close, slick spreading as far as Gen’s hand and precum staining the blankets below. The only thing on his mind now was orgasm, and Gen was over the moon to be able to witness him unravel. 

"Why are you still wearing clothes? You said you were hot didn't you?"

Gen popped open the entire front of Senku's tunic one-handed, fingers dripping with sweet slick. He only briefly disturbed Senku's busy hands by shoving the tunic off his shoulders and down to his hips.

_Undressing him now gets him to feel cooler, and it interrupts his path to orgasm_, Gen thought deviously.

As soon as the offending tunic was gone, Gen repositioned his and Senku's hands.

“Yuzuriha would let you lick her core, burning hot and soft as it gushed slick onto your lips. She'd make such cute sounds as you paid attention to her clit, flicking and sucking it with your tongue.” 

Senku was trying and failing to keep his voice down.

“Taiju would make sure both of you had finished before he finally…”

_ Almost. Almost! _

“Let go inside you.”

Senku came, “Gen! I—!” 

Gen thought it was beautiful how Senku threw his head back, mouth open in a silent scream. He spurted cum onto the blankets and his belly and one last wave of slick coated their joined hands. Gen fucked Senku’s own hand into his pussy through it all. 

When Senku finally started coming down from his high, Gen removed his helping hand and placed the fingers soaked in Senku’s slick into his own throbbing core alongside the hand that was already there. 

Senku stared as Gen fingered himself with a mixture of both of their fluids. 

Gen rolled onto his back, still going, lost in the feeling. 

“Uhnn, Sen-Senku-chan!” Gen’s back arched and he bit his lip as he came. He too made a mess of himself, collapsing next to Senku, boneless from the pleasure.

The two omegas panted in the afterglow, wet from cum, slick and sweat. 

“Fuck, Gen, that was hot.”

“Glad you liked my idea, Senku-chan. Was it sleazy enough for you?” 

“Hmm, I’m not so sure sleazy is the right word, it was more...sexy.” 

Gen was about to continue their banter when Senku pressed their lips together. Shocked, but unwilling to waste this moment, Gen kissed back enthusiastically. 

Senku was an inexperienced kisser, and thankfully a quick learner. He followed Gen’s lead and managed to twine their tongues when he became confident enough.

Gen couldn’t believe it. Senku should be pretty lucid now after cumming, did this mean something more or was he just loopy from the orgasm? 

The kiss broke with a _ smack_. 

“Quite the gentleman aren’t you? Finding a way to make me cum without touching my erogenous zones yourself.” 

Senku got up and swung a leg over Gen, sitting down comfortably on his crotch. His eyes were lidded and teasing. 

“And using my longing for my packmates against me, how insightful of you.”

Senku grinned mischievously and rubbed his rear end against Gen’s cock, which was already beginning to harden again. 

_We're here already, fuck just taking care of me, fuck thinking logically, I want him inside me and I want him NOW. _

“Of course, pack rules are pack rules,” Gen made a serious face, imitating a certain guard almost perfectly.

“Mm, I really think you should fuck me, though.” 

“WHAT!”

Senku laid down on Gen’s stomach and looked him right in the eye. 

“Gen, I’ve thought about this very carefully. You’ve already proven that I can trust you with anything, even my heat, which won’t be sated until someone sates me properly. You’re an omega too, so mating with me has only a 25% chance of producing offspring. You being an omega has a twofold advantage of not setting off Taiju’s alpha protectiveness. My pack will ten billion percent understand, they might even be grateful. You will have looked after me when they couldn’t, and I don’t think either of us can deny our attraction to each other anymore.” 

Gen stared at this brilliant, wonderful, whirlwind omega. He cupped Senku’s face. 

“If you’re okay with this, then I can’t help myself. I’ve wanted you since you first lit that lightbulb that night.”

Senku paused.

“Ew, we’re turning into saps.” 

Gen laughed, too happy to pretend to be grossed out, “You’re right, we are!”

“Of course I’m right! My calculations are never wrong.”

“Leave it to the chief of the Kingdom of Science to tell me why we should fuck using facts and statistics to support his claim.” 

“I’m glad I was able to convince you, now let’s get back to business, mentalist.”

Senku moved against Gen again and sighed in bliss. 

“Aye aye, chief.”

**Notes for the Chapter:**

> I'm going to be editing the previous chapters as I add new ones since I use fics to improve my writing. Not sure how much improvement I'm gonna get from writing smut but it's good practice I guess. I've added a new segment to the first chapter if you'd like to check it out. Just look for the ~ break in the text. Lmk if there's anything that doesn't make sense or there's typos.


	3. Hands On Experience

Senku did eventually get to eat his breakfast, although at this point it was more like lunch.

Gen had proceeded to tease him until he couldn’t take it anymore, wringing every possible drop of pleasure out of him with agile, confident hands.

And Gen? Gen was in heaven. Senku made such wonderful noises in the throes of heat. There were little things he found he loved about making Senku come, besides the obvious. His gravity-defying hair got tangled and wilted a bit, strands of it becoming stuck to his forehead. His legs shivered when he was about to come and he clawed at the bedding beneath him when he finally did. Gen found that he didn’t need to do much to get himself off, watching Senku and rubbing against the bed was enough.

After their little stint, Gen got dressed and left to get some cloths and water to clean them up a bit before the next wave of heat sent Senku back under.

Now that he was more coherent, Senku’s face was on fire.

He remembered calling out Gen’s name and nearly screaming at the intense feelings. There was no way that nobody outside hadn’t heard him. He didn’t even know he could BE that loud. Worst of all (best of all?), the next couple of days would be filled with this. He wouldn’t be able to get a single thing done except fuck and keep himself alive. Well, Gen was helping with most of that.

Gen was amazing, even more so than Senku had known or hoped.

It was a double-edged sword, though. He’d surprised himself that while in this state of mind he was able to convince the mentalist to mate. It kept the heat from getting too bad, but at what cost? Right now he just wanted to hole up in his lab and go back to doing what he did best.

Stupid, stupid biology.

Senku groaned into the pillow he had mushed his face into. This heat even had him insulting biology! Truly blasphemous.

Senku hadn’t noticed Gen’s return during his dramatics and was slightly startled by the small giggle from above him.

Gen set down the basin of water and glided his hand down the curve of Senku’s back. His scientist was adorable when he was embarrassed.

“Hey Senkuuu~” Gen said in a sing-song voice.

Senku offered a muffled grunt.

“You gonna come out or continue suffocating yourself?”

“Im gunoff shuffocat. Go way.”

Gen held back a burst of laughter. Instead, he rid himself of his clothing again and laid half on top of his partner’s still bare body.

“You know, you don’t have to be embarrassed. It’s natural, and it’s only logical.”

Senku made an offended noise at his logic being used against him.

“Besides…” Gen leaned in close. “You were very good.”

That made Senku sit up sharply. Gen rejoiced in the red color spread across his partner’s face, and the rather constipated look that came with it.

“But I barely did anything! You were the one who—“ Senku cut himself off when he realized what he was saying. He facepalmed after a moment and said quietly, “You’re the one who knows how this works.”

“What? You mean you never experimented on yourself? I thought you knew everything.”

“...There’s only so much you can do by yourself. And there’s a difference between knowing how biology works and having...hands-on experience.”

“Hmm… and I assume you were too busy for a hands-on experience? I would have thought you would never pass up an opportunity to experiment.”

Senku gave Gen a _look_.

Gen only smiled, cupping Senku’s face in his hands. He rubbed a cheek gently with his thumb while a couple fingers retreated to rub behind Senku’s ear.

“Then let me teach you, Senku. Let someone else take the lead for a while.”

Senku relaxed and started purring, surprising himself again with how much he wanted that. He couldn’t believe how easily Gen could turn him to mush. It was a little humiliating, but he couldn’t bring himself to care at the moment. He pushed his head into Gen’s hands for more attention.

“You don’t have to worry about anything, Senku-chan. Science won’t disappear if you don’t pay attention to it for a few days.”

Gen leaned forward for a kiss and proceeded to thread his fingers through Senku’s hair. The scientist reveled in it, feeling taken care of for the first time in perhaps too long. He was focused on the kiss, making sure to move his lips in tandem with Gen’s and tilt his head just so. They kissed for several minutes, Gen wanting Senku to really get comfortable before they started again. They separated every now and then to breathe more fully, panting into each other’s mouths.

Gen massaged his hands on Senku’s scalp and eventually reached the base of his skull. Senku jumped a little and broke the kiss.

“Something wrong?” Gen asked.

Senku leaned back a bit and lifted his hand to where Gen had just been massaging. It had felt undeniably good, only that particular spot had an unpleasant memory attached to it.

“No, it’s just—not...there.”

“Okay, I won’t touch you there. Please tell me if you’re uncomfortable with anything else. You’re doing so well, love.”

Senku nodded and didn’t have time to dwell on the pet name as Gen’s hands suddenly gripped his backside. He had to bite back a noise in his throat when Gen smoothly slid him into his lap. Those hands began exploring the soft flesh of his butt and shifting him back and forth to provide a hint of friction.

“Fuck Gen, when did you get this strong?”

“You seem to forget how long you had us pumping the fires for iron you slave driver.”

“Hmm, but the results of the iron and the physical labor is very beneficial for both of us.” Senku drove his hips forward and rubbed his dick against Gen’s, triggering a low groan from both of them and a playful squeeze from Gen’s hands.

“Wouldn’t you agree?” Senku whispered.

Gen shivered at the ghost of breath he felt, “Oooh, you’re a natural, Mr. I-Don’t-Have-Time-For-Romance.”

“I seem to remember a certain mentalist promising to teach me. I’m just applying what I’ve observed.”

Gen laughed, “Just you wait, cheeky scientist.”

He tipped them both forward and pinned Senku into the soft animal skins with an ‘oof!’. They were nose to nose when Gen said,“It’s time for the real lesson.”

Senku gulped in anticipation and nervousness at the sinister grin on Gen’s face. _Is this how other people feel when I do that? _

“Put on your hand on my lips, love, we’ll need some lube.”

Senku put his hand to Gen’s lips and his fingers were given a couple kitten licks.

“Good, but I meant my other lips.”

Senku snorted in amusement.

Gen gave Senku’s hand a nudge in the right direction and sighed when fingers touched his sensitive labia.

Both omegas were entranced by the feeling of Senku’s fingers dragging through Gen’s slick. Gaining confidence, Senku spread Gen’s labia and gained access to his soaked entrance. He ever so slightly dipped his fingertips in. Senku’s unoccupied hand decided to join in by taking hold of Gen’s cock.

In response, Gen widened his stance and gasped, closing his eyes. Senku watched in awe and kept playing. He was making Gen squirm, pant, and lose his mind just a little bit. When Gen dropped to his elbows and pushed himself onto Senku’s fingers more firmly, he understood why Gen had been so captivated earlier. The sight before him made his own pussy ache in emptiness and his dick throb in inattention.

“Enough.” Gen managed to get out just before Senku was about to start thrusting his fingers into his cunt. At this point, Senku’s hand was drenched.

Gen took Senku’s other hand away from his cock and placed it on his hip to steady himself. He lowered his body so both their cocks were just barely touching.

“Now, jerk us both with my slick.”

Senku obeyed eagerly.

The friction of their cocks pressed together and the very knowledge that the wet sounds were from Gen’s slick was impossibly arousing. It was as if Senku couldn’t get enough air into his lungs before he was struck again by the stroke of his own hand and Gen’s dick.

“Aah~ come on! Senku, show me how you make yourself come.”

Gen was shaking and fisting his hands into Senku’s hair, barely able to keep himself from collapsing. Senku picked up the pace and both omegas thrusted into the deliciously calloused hand. Senku twisted on an upstroke and swiped his thumb over both of their heads. Their bodies practically curled in on themselves with the urge to be as close as possible, muscles tensing when they felt their peaks so tantalizingly close. Their legs thrashed about, trying to find purchase on the furs beneath them to drive their hips together. The hut was filled with the sounds of desperation.

“Gen...Gen! Ugh!”

“Senku-chaaan…So good...”

Senku came with a sharp cry, tears pricking at the corners of his eyes.

Gen followed soon after, adding to the spurts painting Senku’s stomach. Once he was done, he rolled to the side and let the air cool his heated skin.

It felt so good Senku could have sworn his brain had stopped working for a few moments there, which was honestly an accomplishment on Gen’s part.

Gen recovered first and began planting kisses all over Senku’s chest and shoulders, praising him all the while. Senku couldn’t help but smile in satisfaction. This smile was quite soft and unlike his usual expressions. Gen loved it. He loved a lot of things about Senku.

Senku lifted his head and laughed at the sensation of kisses scattering his body. He opened his eyes just in time to see Gen lick off a few drops of their shared mess on his stomach. Naturally, he nearly choked.

In retaliation, he sucked one finger into his mouth and sampled Gen’s viscous fluids.

“Wow,” Gen breathed. “You’re really a fast learner.”

“Hey, I’m a good student.”

Reluctantly, they sat up and wet the cloths in the basin. They wiped each other and themselves off in contented silence.

_This is nice_, Senku thought. Then he scoffed at himself, this was more than just _nice_. Maybe he should have thought about that pet name and the fact that he was so happy despite being away from Taiju and Yuzuriha. Maybe he should have been _concerned_ about it. However, he fell asleep too quickly for those thoughts really register.

Gen had to leave again to dispose of the food scraps, dirty water, and cloth. He wished he could clean the bedding, too. Though, as far as he knew, this was Senku’s first nest and disturbing it wasn’t a good idea.

Just as he was cringing at the fact that Chrome was gonna end up having the scent of omega sex on his things, he was assaulted.

Well, not really, but it felt like it.

**Notes for the Chapter:**

> Happy holidays y'all, I'm most likely going to be posting more since I've got free time now. I've got a little bit of an idea where this story is going now, but since I'm making it up as I go along I have no idea how long it's going to end up being. It was originally just for shits and giggles but I might actually put plot in here. *gasp*


	4. Honoring Promises

Evidently, the news of Senku being in heat had gotten out. They were supposed to keep it quiet, damn it. Gen sighed in defeat. Ever since he woke up today, plans were going off-script.

The villagers must have been confused at the sudden lack of ramen and work, and with all of Senku’s noises and scent (lovely though they were), it didn’t take them long to figure out what happened.

Omegas were treasured in Ishigami Village,  _ and  _ Senku just so happened to be the chief, so… 

“Gen! How is he?”

“You seem to have been sating him well! Do you need more water? Blankets for the nest?” 

“I brought some broth. It shouldn’t bother his stomach.”

“It would be so wonderful to have newborns in the village again, especially after everything he’s done for us.”

“Are you keeping up with him? Must be difficult without being in heat yourself.”

Gen chose to push the comment about “newborns” to the back of his mind to unpack later (hopefully quite a bit later), and accepted the broth. 

It wasn’t enough to satisfy their curiosity, though. Gen tried to keep his answers as vague as possible, for the sake of both Senku and himself. Unfortunately, that only made the villagers ask more specific questions.

Kohaku decided to step in and break up the crowd, telling them Chrome should have new orders of ramen ready by now. The villagers trailed off reluctantly.

Kohaku put her hands on her hips and regarded Gen. “I know you said you didn’t need anything right now, but seriously, what do you need?” 

Her offering to help was rather sweet, Gen thought. Kohaku was usually so rough and tumble. Gen found himself smiling more in the time he’s spent here than his performing days. Smiling genuinely, at least.

“I’ll need some of your clothes or blankets,” Gen said, tucking the jar of broth under his arm. 

“Senku’s nest is a little incomplete. I’m sure he’d feel safer with the scent of a complete pack. His real pack isn’t exactly available, after all.”

Kohaku’s face dropped at little at Gen’s last sentence, but she recovered quickly and nodded.

“Do you want me to move some of Chrome’s rocks out of the hut so you have more space?” 

Gen was about to nod, then reconsidered. 

“Actually, he might  _ like _ the rocks. It probably reminds him of Chrome. If he had a problem, he would have done something. You know how he is.” 

Kohaku rolled her eyes, muttered “Good point”, and left.

Gen scurried up the ladder to set the broth next to the drinking water in the hut. Leaning down, he checked the sleeping Senku’s forehead with the back of his hand. Senku was very warm, although not warm enough to be concerned about to start another wave just yet. Gen decided to place a wet cloth over his forehead, just to be safe. 

Doing that gave Gen déjà vu, remembering the aftermath of Magma’s attack. Senku had changed his bandages and monitored his temperature, making sure he was comfortable. At the time, he claimed it was because he couldn’t afford to lose the extra power (physical and mental) that Gen provided. Gen had known, though, that that was only half of the truth.

He’d been interested in Senku from the very first day he’d been unpetrified, and the fondness had only grown. When he found out that Senku was part of a pack already, he resolved to just tease the scientist by flirting, hoping the feelings would die down with time. Now that all of this had happened, there was very little chance of his feelings “dying down.” 

Gen slid down the ladder and waited for Kohaku to return. He set his cheek on his hand. 

It’s not like he had anything against Yuzuriha and Taiju. From what he gathered during his time in Tsukasa’s empire, they were decent people. Senku’s attitude towards them, even while they were away, was evidence enough that they were  _ great _ people. It would be so much easier if Senku’s packmates were somehow flawed; then he’d have the right to dislike them. Alas, that was not the case. 

Additionally, he could tell that Senku’s strong connection to Taiju and Yuzuriha was giving their current pseudo-pack anxiety. Kohaku would always react in some small way when they were mentioned, which was actually a lot (nobody’s told Senku that he tends to brag). Under normal circumstances, Chrome would be running around the hut, incessantly offering help, but Gen hasn’t seen him anywhere all day. Even if he didn’t have feelings for Senku, Gen was sure he’d be frazzled as well.

Instances of packs overlapping in the modern world was pretty common. People form bonds with different groups all the time; it just takes an extra oomph of trust and devotion to turn a friend group into a pack. When two packs form with a member (or more) in common, the packs would usually just merge by spending time together. If things don’t work out, depending on the situation, any number of things could happen next: completely disbanding the packs, the mutual member having to choose a side, one or two people having to leave the pack...things got messy. 

The pseudo-pack was formed on short notice compared to Senku’s original pack. Although, their bonds  _ were _ undeniably strong due to the nature of living in the stone world and working so hard together. The two packs would normally have just tried to merge. Only, the Empire of Might had to be dealt with before that could happen, and that’s not even taking into account the difficulties of merging packs. Hence; anxiety.

Senku was their leader, and Gen, Kohaku, and Chrome were unsure if he would drop them once Taiju and Yuzuriha returned. If he didn’t, were Gen, Kohaku, and Chrome the only new pack members? Or did Kinrou, Ginrou, and Kaseki count too? Kaseki and Chrome were close, as were Kohaku, Kinrou, and Ginrou, but close enough to be part of the pack? And what about Suika? They did take care of her for the majority of the day. 

Gen groaned, feeling a headache coming on. That all sounded so mean, debating whether people counted in their group or not. Developing packs are hard enough on their own without questioning the leader’s intentions. There were so many unknown factors, and as a mentalist, of course he considered all of them.

Gen was saved from his thoughts by Kohaku. She handed him a small bundle of clothes tied with one of her hair ties. She then proceeded to threaten him, saying she better not find slick on her stuff later. Just because she’s doing this doesn’t mean she wants to come in contact with anything sexual concerning them.

Gen debated teasing her, but now wasn’t the time. He just agreed and retreated back into the hut. 

~~~

By the time the sun was setting, Gen had fallen asleep watching Senku sleep. Senku had been roused by the feeling of an impending heat wave, and wanted food beforehand. 

For a moment, he watched Gen sleep in return. His head had bobbed forward in his sitting position, making a goofy little hair curtain. The soft look on Gen’s usually so expressive face was endearing. It was just like when Senku had taken care of Gen when he got attacked by Magma. Senku had watched Gen sleep late into the night as he thought about how to make Cola. 

Gen was so...refreshing. He wasn’t interested in science like Chrome, understanding like Yuzuriha, or enthusiastically strong like Taiju and Kohaku, but he was clever. Incredibly so. It felt so nice to be around someone from the modern world that operated on the same social logic that Senku did. 

They both love battles of wit, both are manipulators, and both think about people in terms of their use. Being nice to people just so happens to be the best way to use them. And at the end of the day, there was no denying that they cared about the people they claimed to be using as tools. 

Senku wanted his packmates, but Gen and the others meant something to him. He wasn’t sure how well he could force that down. He had a job to do. They all did. Could he afford to cause social drama at a time like this? Was it worth it? Did being with Gen mean losing Taiju and Yuzuriha?

_ No. _

_ First objective: clear mind. _

_ Second objective: cool down. _

Senku went over and promptly dunked his face into the water bucket. 

He was only doing this to get through his heat, and then he could go back to his lab and have some peace. That’s it.

“Having a bath, are we?” 

Apparently, the splash had woken Gen.

Senku flicked water at him. 

Gen just laughed and offered him a jar of broth, which Senku drank eagerly. 

“Slow down, you’re gonna get sick.”

Senku did. The broth was only slightly warm, hearty enough to calm his stomach, and mild enough that it didn’t aggravate Senku’s heightened senses. Speaking of which, the water that had been a relief earlier was now running down his neck and chest in droplets that felt like the barest hint of a touch. The drying water also made him shiver slightly, his skin being simultaneously cooled by evaporation and warmed by the heat. 

Senku nearly dropped the jar when he was finished. Scents were swirling around him, luring him into his next wave of heat. Gen...Chrome and...Kohaku? Senku scanned his nest and spotted a bundle of Kohaku’s clothes. He crawled on all fours and hastily positioned the articles of clothing on the edge of the nest. He paused when he picked up Kohaku’s hair tie to rub the sturdy rope between his fingers, the texture pleasant. It all added a hint of Kohaku to the room. 

_ Perfect. My nest is perfect. Missing one thing, though... _

Senku stopped admiring his nest and whipped his head towards Gen, who was patiently waiting on the sidelines. 

_ That’s not right. _

Normally, an omega would wait for their mate or partner to give praise before declaring the nest perfect. Senku was not your normal omega. He knew the nest was perfect. He dragged Gen into it by the arm. 

“Someone hasn’t made good on their promise to fuck me,” Senku said when he had Gen under him.

He didn’t give Gen time to respond. He just dove in for a passionate kiss. 

_ “Why do you keep getting dressed?!” _ Senku whined when he remembered Gen still had his thinnest layer of clothes on. Senku grumbled incoherently as he rid Gen of the offending fabric. Gen just watched in amusement, becoming aroused by Senku’s warm hands undressing him. Once he was bare again, he grabbed Senku’s hair and reunited their lips. 

The kiss was ravenous this time, both of them feeling the rising energy between them. They molded their mouths and battled with their tongues. A string of saliva snapped when they separated. 

Gen pulled Senku closer and kissed a line down his jaw to his shoulder. He had full access to Senku’s scent gland, and was encouraged by Senku sighing and tilting his head to the side. Gen latched on to the spot between his partner’s neck and shoulder with vigor. 

Their lower halves were becoming more demanding. Senku was squirming, unable to decide between squeezing his thighs for some relief and keeping his legs open to entice Gen. He made a groaning whine in frustration.

“Shhh. I’ve got you.” 

Gen abandoned the soft hair and gripped Senku’s ass to pull him up farther. Their dicks were aligned, and Gen decided to take full advantage of that by wrapping a hand around them. He left his other hand on that plump butt to help Senku thrust.

“Ah! Ahhh!” Senku could no longer hold his head up and had to drop it into Gen’s neck.

“You’re so responsive. I like how you always let me know that—ah! I’m doing good,” Gen said, licking his lips.

At some point, Gen lifted his hips and bowed his back, getting Senku to do the same. It was a little uncomfortable and clumsy, but when it worked, it was pure ecstasy. They thrust against each other, their dicks, balls, and labia rubbing together in the most delicious of ways. 

It was like everything was turned up to eleven all of a sudden. Gen felt like he was lying on a cloud, unable to worry about anything but the lava rushing through his veins. The weight of Senku’s body was above him, exuding the smells of heat, sweat, and sex. Senku’s mouth was on his scent gland just like it had been this morning, only more confident. Gen was overwhelmed by Senku’s touch wandering his body and occasionally stopping to squeeze his hips or flick his nipples.

_ That’s new. _

Senku bit Gen’s scent gland hard, and made an indignant noise, trying to convey what he couldn’t articulate. 

_ I need you in me now! Please just… _

Gen relaxed his back and returned his hands to Senku’s rear. Senku sat up a little with his arms on either side of Gen’s head. Gen gave his best impression of a questioning look.

Senku looked at him like,  _ If you don’t fuck me right now, I swear to God, mentalist, I will..! _

He didn’t have time to finish the thought when Gen positioned himself and basically dropped him onto his dick. If there was one good thing about heats, Senku thought, it was the fact that he was so loose that prep wasn’t needed. 

It felt so good. It felt so goddamn good. 

All of Senku’s instincts were roaring in happiness as he bounced up and down on Gen. The empty feeling was gone. Every time Gen hit home inside his soaked pussy, it was bliss. Senku completely forgot himself, his science, and the stone world in favor of this small moment in time that he and Gen had created. He had counted the seconds for thousands of years, but this moment felt like it was never-ending and going by too fast at the same time.

“Gen...yes, yes! Harder! I need—!!” 

“I know, I know,” Gen said so breathlessly it almost wasn’t words.

Gen could feel the fluttering of Senku’s pussy. They were both so close to the edge. It was so hot and wet, he could feel Senku’s inner muscles grip him on the slides out to try to keep him inside. 

When Senku finally came, he ran his nails down Gen’s chest and let out a shuddering sound. Gen felt the release on his stomach and around his dick nestled firmly inside Senku. With a gush of slick from his own cunt wetting the nest below, Gen came, too. 

Senku sighed, his pussy was still throbbing in orgasm when Gen began releasing his cum. The feeling of being filled was the final puzzle piece. He let out a powerful, content groan.

As both of them were reeling from their orgasms, neither registered how exhausted they were for a few seconds.Then, Senku just collapsed.

Gen rolled them onto their sides, and they panted together for a good while. Gen studied Senku’s red, sweaty face, eyes closed and mouth trying to smile through frantic breathing. He rested his forehead against Senku’s and touched their noses ever so slightly. 

This made Senku open his eyes. What Gen saw in those deep, red eyes gave him hope that he and Senku would be able to do this again. Perhaps that hope was a bad thing, but Gen did not care anymore. 

When they had calmed down fully, Gen said, “Hey, Senku?”

“Yeah?”

“You triggered my heat.” 

**Notes for the Chapter:**

> Special thanks to MoralCode for being my beta!


	5. Heat of a Summer Storm

**Notes for the Chapter:**

> Happy new year and happy birthday Senku! This chapter would’ve come much earlier but me n my beta had a lil misunderstanding 😅  
Hope you enjoy!

The two omegas were truly exhausted. Senku was too deep in heat to really do anything about Gen’s situation, and Gen’s body was busy readying him for his own heat. The direness of the situation was a bit undercut by the fact that both of them were asleep within minutes.

It was after midnight when Senku awoke again. As the sleep cleared from his eyes, he stared at Gen’s slightly flushed, sleeping face. 

Senku could smell it in the air; the next morning his heat mate would be just as demanding as him. 

Something woke him up, though; he should’ve been tired enough to sleep through the night. There was something wrong, something very wrong. He just didn’t know what, yet. 

He closed his eyes and drank in the smells that permeated the air for a few moments: Gen’s herbal sweetness, Chrome’s metallic tang, and Kohaku’s woodsy sharpness. It wasn’t often that he was surrounded by all of them at once. Each one was comforting and unique in their own way. Senku felt almost like he was getting high on the scent of his pack. The weight of rebuilding civilization was lifted from his shoulders, if only for a short time, and he felt like he was filled with helium, like he was lighter than air. 

_ Add to that all of the skin to skin contact with Gen, and my endorphins must be working overtime. _

The nest felt so much softer than it actually was, and he could hear every slow breath that Gen took. In and out and in and out. It was calming, yet, despite that, his body refused to let him fall back asleep. 

_ Something is wrong. But what? What’s missing?  _

Gen, Chrome, Kohaku...Yuzuriha and Taiju.

_ I need them. I need their scents, too. I need everyone’s! _

Senku started panicking. 

_ I don’t have anything! How do I get them?! How?? _

Then he remembered the one thing he had that his packmates had given to him.

Senku carefully snuck out of the nest and cracked the door of the hut.

The night was a bit chilly, but there was no wind. He could sneak out and get back in quickly. The only problem was that he wouldn’t be able to tell if danger reared its ugly head. 

_ I have to: I need them! _

Senku wrapped himself up in his tunic and slid down the ladder. 

He didn’t spend much time outside at night, since he required daylight to work. The lack of light pollution made nighttime significantly darker than he remembered. With no moon to illuminate the clearing, the only light came from the band of stars that formed the Milky Way above him. 

Senku darted across the clearing to the observatory and climbed the ladder to the lip, where the floor met the curved walls.

There was a smaller ladder made out of simple wood slats that went up the side of the wall on the outside of the dome. Senku felt around for it and made sure he had a firm grip before climbing. Every time he wanted to go higher, he had to make sure he had stable footing. Otherwise, he would fall. It was slow going, which only made his anxiety worse.

_ Faster, faster, I have to get back to Gen. _

When he finally got to the top of the dome, he sat on his feet and reached up to untie the Kingdom of Science flag. Once he had it in his hands, the anxiety faded.

Senku rubbed his hands and neck against the fabric, feeling the coarse stitches made by Yuzuriha. It didn’t smell like his packmates anymore, but just the fact that it was theirs was enough. He sighed and squeezed it to his chest before securing it around his neck like a cape.

Senku was practically shivering with excitement, which made him clumsier. So, halfway down the wall, his foot slipped.

He skidded down the remainder of the dome, hands scrabbling for purchase. He was able to grab the lip of the observatory floor, but it didn’t last long and he ended up falling to the ground. 

Senku landed on his back and rolled. He gasped, trying to get air back into his lungs. Falling from that height would’ve been really bad if he hadn’t slowed himself down. He would’ve been out of commission for a lot longer than the time it took for his heat to pass.

After getting his breathing back to normal, Senku tried to stand and found that he couldn’t. 

He was dehydrated and hot, making his vision swim when he sat up. He leaned his head against one of the posts holding up the observatory and whined. Senku was too exposed here, and his instincts knew it. 

_ Nest! Nest! _ His brain shouted helpfully.

He wrapped himself in the flag and whined louder in the darkness. 

The whine of an omega in distress was shrill and long, designed to carry. If anybody was up at this ungodly hour, they should be able to hear it.

Somebody did, and they broke the tree line in seconds. Senku looked up, hoping to see Kinrou or Kohaku. It was Magma. 

Senku’s entire body tensed as Magma approached, radiating predatory pheromones. Adrenaline shot through Senku like a lightning strike, forcing his body to stand. He immediately put the posts and ladder of the observatory between him and the alpha. Magma stopped a few feet away, leaving the obstacles between them for now, and gave Senku a stare that could make flowers bend their heads in submission. Senku refused to bend his head, even though it was probably a bad idea.

Magma growled and lunged forward. 

_ Bad idea! Bad idea!! _

Senku just barely dodged and made a break for Chrome’s hut. As he ran, a screaming cry escaped from his throat. He’d just barely gotten to the ladder when his cape was snagged. Senku choked and grabbed the tie on his neck to pull it away from his windpipe. He felt Magma pulling him back, bit by bit. 

_ No no no no no no no no no!! _

Suddenly, the pressure was gone and Senku collapsed on his hands and knees, breathing raggedly. He looked back to see that Kinrou had knocked Magma on his ass, his spear pointed at the aggressive alpha’s throat.

Ginrou appeared by Senku’s side. “Senku! What are you doing out here? You should be in your nest!”

Senku just whimpered and pulled the flag tighter around himself, shaking.

Ginrou realized this wasn’t the time to be scolding him.

“Okay...okay, let’s just get you back in there.”

He was able to get Senku’s arm around his shoulders and move his own arm around Senku’s waist to support him. They hobbled awkwardly over to the ladder, and then Ginrou practically dragged his fellow omega’s dead weight up it.

Ginrou shoulder checked the door and set Senku inside his nest. Senku immediately untied the flag and cuddled it between himself and Gen. He was still shaking.

Ginrou was frozen, unsure of what to do. Magma had just tried to catch Senku to do...who knows what with him! And Gen was clearly in pre-heat. In the end, he decided to just sit at the edge of the nest and watch the door. What a disaster.

Kinrou showed up a little later with a bucket of freshwater. Ginrou convinced the two omegas to sit up. Trying not to let his distress leak into his scent, he made sure Senku and Gen had enough to drink before they fell back into dreamland. 

This night’s watch had gotten...interesting. What the hell was he gonna tell Kohaku?

~~~

Gen was roused by the sun shining directly into his face from one of the windows. When he shifted out of the way of the sunbeam, he registered the fact that Senku had wrapped all his limbs around him like an octopus. There was some cloth in between them...the Kingdom of Science flag? When did...?

Senku pressed into him further, and Gen was immediately distracted. A shiver took hold of his body and triggered a wave of slick. It was then that he noticed how painfully empty he felt.

Senku lifted his head and blinked groggily. 

It briefly occurred to Senku that the deep aroma of lavender and flowers was much stronger than last night. 

“Gen,” he whispered.

Gen made a noise of discomfort in response, then yelped when Senku pounced on him.

When two omegas go into heat at the same time, one usually takes the more dominant role in order to satisfy both of them. Gen was unsurprised that Senku would take the lead.

Senku licked a long stripe up Gen’s neck, tasting the scent gland there and reveling in it. He could taste Gen on his tongue now. He continued abusing the gland with his tongue to get more. A rumbling purr escaped from deep in Senku’s chest, which prompted Gen to purr back. Gen was writhing from just his scent gland being given attention. 

Senku pressed his weight down and brought his hands to Gen’s sides to keep him still. When Senku continued to do nothing but leave hickeys on his neck, Gen hooked his legs around Senku’s waist and used his heels to push his crotch into Gen’s. Senku was wearing his tunic again, so the friction wasn’t much, but it was enough to cause his head to snap up. Senku moaned into the air and bit his lip when Gen did it again. 

“Senku, please! Hurry!”

The emptiness inside Gen was starting to get to him. He grabbed Senku’s hair and made those ruby reds look down at him. Gen pleaded with his eyes, and, evidently, Senku got the message.

The scientist wormed an arm underneath Gen and grabbed the nearest piece of bedding, which happened to be the bunched up Kingdom of Science flag. He used it to prop up Gen’s hips. He also managed to pull up his own tunic so his leaking cock became exposed. 

Gen licked his lips when he saw that Senku was wet enough to have covered his own thighs in slick. Oh, how he’d love to eat out the beautiful creature above him...That thought was quickly forgotten when Senku kissed him, though. 

Senku was able to position himself properly even as he put his all into the kiss with the desperate omega beneath him. Drool started to run down the side of Gen’s cheek when he felt the head of Senku’s cock brush his folds. 

Senku hugged Gen so their bodies were completely flush and hooked his chin over Gen’s shoulder so he could continue drinking in the lovely heat scent as they mated.

Gen made a drawn out, relieved whine when Senku finally thrust in. The hands that had been holding onto Senku’s hair moved to his back to clutch the fabric of the tunic. 

Senku’s movements were hesitant at first, never having done this before, but soon, he’d found a rhythm and was pounding into Gen eagerly. He was rather rough, fueled mostly by instinct at this point, but Gen’s pleased noises never stopped, so he didn’t, either. 

Gen’s insides felt incredibly soft. Senku felt almost as if the heat coming from Gen’s body would burn him. He shuddered violently on top of Gen when he ground his hips in a particularly long thrust. He went as deep as possible, trying to chase away the emptiness that he knew Gen was feeling.

Senku gave a few more of those long, deep thrusts, and it was all over for Gen. His hands scrabbled at Senku’s back messily, and his legs automatically locked Senku’s hips in place to keep him inside. Senku quickly propped himself up so he could watch Gen’s face as he came. 

Gen’s mouth fell open in a silent scream as he painted them in come. Senku started moving again as Gen orgasmed until he, too, couldn’t hold on any longer. His thrusts shortened when the waves of pleasure began crashing through his body. Senku was trying to groan and purr at the same time, so his voice came out raspy and loud. 

“Gen...” 

The two of them finally relaxed, resulting in a heap of floppy, satisfied, soaked omegas. 

Senku sat up when he could think again, and winced at the small puddle of slick and cum they’d made in the nest. Then, he remembered the flag and pulled it out from under his partner. 

It now had a small slick stain and smelled like his and Gen’s coupling. He brought it to his face and inhaled. His crisp, fiery scent had mixed with Gen’s soft, flowery one to create a sort of humid, ozone scent. It was like petrichor or the aftermath of a tree struck by lightning. Together, they were a summer storm. Senku wished he could bottle this smell so he could appreciate it whenever he wanted.

Gen was already asleep, so Senku just discarded his come-soaked tunic, laid down, and covered their bodies in the flag. The scent of their union was so comforting that Magma’s assault became only a half-forgotten nightmare.

~~~

“What do you  _ mean _ Chrome’s gone??” Kohaku nearly screamed. “Where could he have gone? Somebody check the nearby caves!” 

_ First Senku’s heat, then Magma acts up, and now this? What’s next? _

“Kohaku?”

“What.”

“Um...I thought you should know that...Gen’s in heat.”

Kohaku broke her staff in half.


	6. Reassurance

They’d scoured the nearby forest and caves, the village, and even the sea below. Chrome was nowhere to be found, and all they’d gained was a panicked village. Kohaku sent Ginrou to look after Senku and Gen while Kinrou got the job of keeping an eye on Magma (who seemed pretty happy about Chrome’s disappearance). The sun was just starting to set, and if they didn’t find him soon, they’d either have to spend the entire night searching with torches in large groups or hope he survived through the night. 

They’d been doing another round of searching the forest when Suika’s watermelon rolled up. She popped out and told them to follow her. Apparently, her dog had found Chrome’s scent trail. 

Kohaku gathered the rest of the search party, and the team rushed along behind Suika’s puppy. They skidded to a stop near the top of what looked like a hill. The villagers didn’t often come this way, so no one had thought to look here. The place was out of the way, swerving sharply east from where Kohaku gathered hot water for her sister. 

Confused, Kohaku walked further to the top of the hill. Everything seemed normal until her feet nearly gave out beneath her. Kohaku caught a glimpse of the face of a steep cliff, perhaps caused by a landslide, stretching far below her. Turquoise immediately pulled her back from the edge, her heels shaking some stones loose, which echoed as they bounced downward. The drop off was hidden by the thick undergrowth of the surrounding area. The land curved in such a manner that all those who came this way would mistake it for a simple hill. 

After catching her breath, Kohaku joined the others in looking around confusedly. Suika’s puppy wasn’t leading them anywhere anymore.

“Did he lose the trail?” a villager named Soyuz asked.

Suika consulted her pet for a moment, then shook her head.

“No, Chalk says this is where Chome went!”

Kohaku carefully went back to the edge and peered over. 

“CHROME?!” she called, afraid that she would see a broken body clad in blue at the bottom of the cliff.

“Kohaku??” 

Kohaku’s hawk-like eyes soon found where that voice was coming from. A ways down the rock face, there was a familiar arm waving frantically out of a small crevice. 

“CHROME! What are you doing down there?” 

The rest of the group hurried to the edge of the cliff to see. 

“I can explain later! Can someone please get me out first??” Chrome poked his head out of the crevice.

“Can’t you climb up?”

“There aren’t any sturdy footholds! I had to jam myself in here to keep from falling all the way down! One of my arms got banged up pretty bad.”

Kohaku sat back and thought for a moment. Most of the stones and cracks that could serve as footholds seemed rather loose and crumble-prone. Not even the lightest of the people here would be able to get to Chrome safely, let alone bring him back up with them. They could use a rope, but Chrome can’t climb with a bad arm. If someone went down to get him, would the rope be able to hold two people at once? The rope they made wasn’t very heavy duty. If only Senku were here…

_ Wait a minute... _ Kohaku was suddenly reminded of how she met Senku in the first place.

“Turquoise, Soyuz! Get back to the village and get Kaseki and a ton of rope!”

“How are we going to get him out?” Suika asked, worriedly.

“We’re going to make a pulley system.”

~~~

Senku woke to a commotion coming from outside the hut. Finding himself surprisingly coherent, he wrapped himself in a blanket and cracked the door to the hut.

“Ginrou? What’s going on?”

The omega standing guard jumped slightly at his voice. “Nothing, Senku! Just go back to bed; we’ve got everything under control.”

Senku stared at the bustling villagers skeptically.

“What do you mean, ‘under control?’ What needs to be controlled?”

“Ummm...nothing?”

“I may not be Gen, but even I know when you’re lying, Ginrou.” 

Ginrou froze, “I have no idea what you mean, chief! Chrome’s going to be fine!”

Senku paused and went back inside the hut. Ginrou sighed in relief, thinking he’d convinced him. The relief didn’t last long as Senku was soon back and climbing down the ladder toward him shakily, dressed in a spare set of Chrome’s clothes.

Ginrou waved his arms in protest, “Senku! What are you doing?!”

“If something’s wrong with Chrome, I’m going to help.”

_ Crap.  _

“But what about Gen? Don’t you two need each other right now?”

“Yes, but he’s not in immediate danger. Being with Gen has managed to buy me some time when I’m not begging to be fucked. You will tell me where my packmate is, Ginrou.”

Ginrou blinked.  _ No point in trying to hide it now _ .

“He...fell down a cliff and got trapped in a crevice. They’re using pulleys to get him back up.”

Senku’s anxiety increased tenfold. If he wasn’t in heat, he might have been able to hide it or tamp it down with logical thinking, but at the moment, he was unable to prevent his thoughts from spiraling out of control.

_ What if the pulley fails? What if Chrome falls? I can’t lose anybody else...What if...What if… _

He shook his head and grabbed Ginrou’s arms. 

“Where?” he demanded.

“Um, east of where Kohaku used to get hot water?”

Senku started running in that direction as soon as Ginrou stopped talking.

“Wait! Senku! You have to stay in your nest!”

Senku picked up the pace, ignoring Ginrou’s protests. Being in heat allowed him to use his heightened senses to track where the rescue team went. Unfortunately, it took even less time than usual for him to run out of stamina, and he was forced to slow to a speed walk instead of a run. 

Despite his slowed pace, Senku’s anxiety kept his breathing heavy. He resorted to taking deep whiffs of the spare clothes he was wearing, trying not to trip over exposed tree roots as he went. Chrome’s scent calmed him just enough to keep going. At the same time, though, the scent of alpha irritated his heat, and Senku could feel it beginning to spread out from his lower belly again. He had to hurry.

Just as he was scrambling up a short incline, he caught sight of Chrome and the rescue team! Chrome’s blue clothes were darkened with blood on one side, and his arm and head were wrapped in bandages, but he was smiling.

Senku broke into a run again and collided with his packmate in seconds. Chrome made an ‘oof!’ sound and backed up a few steps. 

“Senku?!”

“Senku! What are you doing out here?! I thought I told Ginrou to watch you!” 

Senku responded by strangling Chrome in a hug and yelling in his face, “What were  _ you  _ doing falling down a cliff, rockbrain?!” 

_ Rockbrain? _

“He was trying to get to the Empire of Might to find Taiju and Yuzuriha. Thought they might help you with your heat,” Kohaku said.

“You--” Senku buried his face in Chrome’s neck to get more of the alpha’s comforting scent. 

“Idiot, idiot…” Senku whispered, giving Chrome’s chest a soft hit.

Chrome was unsure of what to do with himself at the moment. He felt bad for endangering himself and making everyone upset, he was scared of what Kohaku might do to him later once she got the chance to really scold him, and he had an armful of an omega in heat acting uncharacteristically emotional. Chrome ended up just hugging Senku back as best he could with his injured arm. 

“Okay, Senku, let’s go back to the village. Gen’s probably wondering where you went,” he said as gently as he could. He felt Senku nod, not letting go of him.

Chrome maneuvered Senku into a sort of half-hugging/holding hands configuration so they could walk. Chrome could smell the anxiety coursing through Senku, which made him feel even more guilty about the whole situation.

When they returned to the Kingdom of Science, a swarm of villagers checked Chrome over thoroughly for any further injuries. Senku stayed by his side the entire time. They encountered Ginrou, who Kohaku couldn’t bring herself to scold too much, since he didn’t leave his post.

After everything died down, Senku still wouldn’t let go of Chrome. He was bemusedly dragged into his hut and Senku’s nest. Nobody tried to stop them, finding it unnecessary to argue with their chief, who was clearly in distress from almost losing a packmate, even if he only showed it through his scent and by sticking to Chrome like sap. Everyone understood the clinginess. 

_ I can’t believe this is happening. The whole reason I went to get Yuzuriha and Taiju was because I thought Senku didn’t see me as a packmate and I wouldn’t be able to help him! _

Chrome didn't have much time to dwell on that because when he entered his home, he was hit with a tidal wave of scent. Chrome could immediately tell that Senku and Gen had mated in here.

_ In MY hut, on MY bedding.  _

Seeing Senku in his clothes and smelling of heat had been arousing enough. Now? The thought of pinning Senku down and attacking his neck was so tempting it was nearly impossible to resist. So, Chrome stood awkwardly at the edge of the nest, stiff and unsure of what to do. 

On the plus side, Senku had visibly relaxed. Chrome could tell that his next heat wave had arrived, too. Senku’s skin was flushed pink, he was panting ever so slightly, and his eyes were lidded. Chrome couldn’t tear his eyes away when Senku dove into a welcomed kiss with Gen. It seemed Gen had been woken by a new heat wave, and had only missed Senku for a short time. Gen’s sleepy expression quickly turned lust-filled when Senku sat in his lap and pressed their lips together.

Chrome shivered as he watched them. Two incredibly smart, talented omegas, in heat, making out right in front of him, and...oh god...Gen put his hands on Senku’s hips and moved them in a slow circle. Senku soon got the idea and began gyrating enthusiastically against Gen. The contrast between the dark blue of the clothes and Gen’s soft, pale skin was striking. Chrome’s spare clothes were baggy on Senku, a fact which did not help his current inner struggle at all. The constant movement of Senku’s hips were causing the pants to bunch up and slip off a little. Gen’s wandering hands found their way underneath the shirt, and, after a moment, Senku made a soft, whining noise into the kiss.

Chrome’s head was spinning, overwhelmed. He was sure his face was beet red. He couldn’t move because just that was enough to cause friction against the  _ very  _ interested cock in his pants. Maybe he could sneak out? The omegas were clearly...busy. If he stayed here any longer, he might do something stupid. Chrome started inching toward the door.

Gen was so absorbed by Senku and lingering sleepiness that he hadn’t noticed the clothes Senku was wearing were Chrome’s. He broke the kiss and put his face against Senku’s chest to take a deep inhale. 

_ Alpha...anxiety… _

He could tell the anxiety came from Senku, so he purred and wrapped around the omega in his arms, pressing their bodies together fully. Omegas were like cats; squishing and cuddling them while they were upset gave them comfort.

Senku purred back and gave a weak little thrust with his hips. He would need more than cuddling soon. Gen heard movement and opened his eyes to see Chrome, poor, flustered, aroused, Chrome, trying to sneak away.

“And where do you think you’re going?”

Chrome froze at the sultry sound of Gen’s voice.

“I--um…”

Senku climbed off of Gen and the two of them crawled over to Chrome like predators stalking their prey. Chrome visibly gulped. They pulled him down by his shirt straight into their nest. 

“Little alpha~,” Gen sang sweetly while his expression was anything but. 

Chrome looked equal parts horny and terrified to have a naked, devious Gen on top of him.

“You made Senku-chan very worried. Why don’t you make it up to him, hmm?” 

Chrome could only nod, making Gen smile and back up to make room for Senku, whom had discarded the restricting pants.

Senku decided to straddle one of Chrome’s thighs and lie down on top of him, sighing as he basked in the alpha’s presence. Chrome could now feel Senku’s breath ghosting across his neck and hardness pressing into his hip. Gen was lying on his side, trailing his fingertips teasingly along both of his bedmates’ bodies. If asked, Chrome would deny that his hands shook slightly when he placed them on Senku’s hips. Make it up to him, huh? He seemed to enjoy grinding on Gen earlier. Maybe he could continue that? He had to show Senku that he was totally and completely fine. That is, he had to convince Senku’s omega instincts of that, which could only be accomplished through touch.

He propped up the leg that Senku was straddling to provide leverage and copied what Gen was doing earlier, coaxing Senku into grinding his hips long and slow. This caused Senku’s thigh to press right into Chrome’s crotch. Chrome sucked in a breath at the barely-there rhythm from Senku moving his hips round and round, back and forth. It was lazy and infuriating and so incredibly wonderful. 

Unable to handle how slow things were going, Chrome’s hands, which were still resting on Senku’s hips, sneaked past the baggy blue shirt that didn’t cover Senku’s ass whatsoever. He gave a firm squeeze, which elicited an eager noise from Senku. Lost in the fog of his own hormones, Senku stared up at Chrome, pushed his ass back into his warm hands, and arched to grind his pussy up Chrome’s thigh. There was no doubt in Chrome’s mind now that he would leave this hut with slick-stained clothes. He gripped Senku’s ass tighter and started helping with the thrusts, trying to find a pace that suited the desperate omega above him. The warmth of Senku and Gen was amazing: cozy, but at the same time, wildly intense. 

Gen was smiling happily from his position cuddled up to Chrome’s other side. The scent of Chrome was being imbued onto their skin and into their nest. He couldn’t help the occasional twitch of his hips, his body begging for stimulation of any kind. He watched Senku writhe on top of Chrome, loving the roughness of the clothes against his sensitive nether regions. 

When Senku started getting impatient, Gen reached over to one of Chrome’s hands and moved it to where his fingers just grazed Senku’s soaked folds. Senku’s whining increased in volume and he dug his fingernails deep into Chrome’s shirt to ground himself. The teasing was becoming unbearable. He wanted something inside him so bad! 

Senku knew that begging for Chrome’s knot was asking for trouble, yet he couldn’t bring himself to stop the words from leaving his mouth. 

Chrome was nothing short of tortured by Senku’s request. What he wouldn’t give to sink into the pillowy wetness that he could just barely feel from dipping his fingers past Senku’s yielding folds. He nearly gave in and rolled them over to get between Senku’s legs, but he forced himself not to by closing his eyes, curling his body, and rutting into Senku’s thigh. 

_ I can’t, I can’t!  _ Chrome chanted to himself.

He focused completely on getting Senku to come. He dipped his fingers increasingly deeper into Senku’s pussy every time he stroked his fingers across it. He released his bruising hold on one of Senku’s buttocks and gave the omega’s neglected cock some attention. Gen joined him by pulling Senku’s face to the side and kissing him as his hand joined Chrome’s in the slicked mess at Senku’s pussy. 

Senku broke the kiss to pant out his pleasure in little ‘Ah!’ noises. He was so, so close!

It was all over when Chrome gave an unexpectedly deep thrust with his fingers and Gen pushed on his lower back to make him grind into Chrome one last time. Senku spurted all over Chrome’s clothes and hands, giving weak little twitches of his hips the whole while. 

Chrome drank in the sight of Senku, mouth open and eyes closed in the height of his pleasure. Soon, though, the expression morphed into one of satisfaction, which, in Chrome’s opinion, was nearly as sexy, if not just as so. Senku sighed happily and slumped to the side, no longer straddling Chrome’s leg. 

When he opened his eyes again, he gave Chrome the smallest of smiles. Chrome had never seen anything like it. The smile was barely there, yet it held such warmth, gratitude, and relief that he knew Senku was thanking him without any words being spoken.

_ I really am his packmate. _

The revelation was like a cool splash of water on a blazing hot day. It felt so good to be  _ sure _ . And speaking of packmates, he had one more to take care of.

Gen was practically ravenous after watching Senku come, mouthing at Chrome’s neck and trying to bring Chrome’s calloused, sturdy hands down to where he needed them the most. Feeling confident in his self control now, Chrome rolled on top of Gen and gripped his thighs. He pulled Gen down so that their crotches met perfectly in a hard, slow grind. Gen gasped, legs quivering. It wouldn’t be long now. Chrome kept up the purposeful, rough pace, grunting a little with the effort. Gen turned his head to look at Senku, who was clearly enjoying the show. On Chrome’s next grind, he made an extra little thrusting motion, which tipped Gen over the edge. He spread his legs even wider, arched his back, and moaned, feeling every pulse of his orgasm in both his cock and his frustratingly empty pussy.

Chrome sat up fully, panting and still hard. He extracted himself from Gen, who was now reaching for Senku for some post-orgasm cuddles. Every bone in his body was screaming at him to stay and satisfy his packmates again and again. He had to shake his head to dislodge those urges. He’d managed to control himself for this round, but he couldn’t guarantee that that control would last for a second round. Plus, he had to rest his injured arm after all that activity. The pain was just starting to return as his body was settling down from the high of being smothered with pheromones. The important thing was that he’d reassured Senku’s instincts of his safety. His job here was done. 

So, Chrome made sure Senku and Gen were comfortable, and left. The fresh air was both disappointing and relieving. He asked Ginrou to bring the omegas some food and water and walked away awkwardly to take care of his erection somewhere private (specifically, somewhere not stinking of omega sex).

**Notes for the Chapter:**

> I had to stop writing for this back in winter because my school life got VERY intense. With me being stuck at home now though, I'm going to start posting again. I can't make any promises as to when new chapters will be out but so help me I will NOT abandon this story. I hope you're all well! Stay safe <3


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